Aspherical Multifocal Intraocular Lens

ABSTRACT

A multifocal intraocular lens has an anterior lens surface which includes a first optic of a first radius and a second optic of a different radius. The posterior surface of the lens include an aspheric surface.

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention is for an intraocular lens that is typically used as a replacement for the natural lens of the human eye. In the event that the natural lens of the human eye is removed, for example during cataract surgery, an intraocular lens is typically implanted in the lens capsule as a replacement for the natural lens.

2. Description of Related Art

There are several types of intraocular lenses (IOL) that have been developed. They include aspheric lenses, multifocal lenses and accommodating lenses. Also improved haptics for securing the lens within the lens capsule have been developed. These designs to some extent result in aberrations and create a halo effect or result in reduced contrast and/or brightness.

BRIEF SUMMARY OF THE INVENTION

The current invention overcomes the drawbacks in the prior art with a unique configuration. The lens of the current invention is formed as an aspheric lens with an added lens surface formed on the posterior portion of the lens. Integral with the lens is a haptic system that securely mounts the lens centrally within the lens capsule and thus minimize any “halo” effect or other aberrations.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic view of the human eye.

FIG. 2 is a side view of a conventional intraocular lens.

FIG. 3 is a side view of an intraocular lens according to an embodiment of the invention.

FIG. 4 is a front view of the lens shown in FIG. 2

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1 it can be seen that the relevant portions of the eye for purposes of this invention are as follows. Eye 100 has a natural lens capsule 110 in which the natural lens is located and pupil 113, which is surrounded by iris 116. The area forward of the lens capsule 110 is generally referred to as the anterior chamber 112 and the area rearward of the lens capsule 110 is referred to as the posterior chamber 132. The lens capsule 110 is held in place by ciliary zonules 133 which extend between the lens capsule 110 and the ciliary body 118. The space 131 between the iris 116 and the ciliary zonules 133 is referred to as the ciliary sulcus 131. The eye also includes cornea 114, sclera 122, choroaid 124, retina 126, fovea 128 and optic nerve 130.

For cataract surgery, a small incision is normally made at the junction of cornea 114 and sclera 122 and the natural lens can be removed from the lens capsule 110 by phacoemulsification, for example. An intraocular lens (IOL) is then implanted within the lens capsule through the same initial incision.

FIG. 2 discloses a conventional aspherical lens 10 which includes a central lens portion 15 having opposing convex lens surfaces 14 and 13. Suitable haptics 11 and 12 extend outwardly from the lens portion 15 for securing the lens within the lens capsule.

FIG. 3 illustrates an embodiment of the invention. Intraocular lens 20 has a posterior surface 24 which is aspherical in shape. Posterior radius of surfaces 29 are of equal value. The anterior surface 51 of lens 20 has a first aspherical lens surface 23 which has a radius equal to radius of surfaces 29 and a second lens surface 27 of a smaller radius, thus forming a higher power lens 26 than that of lens surface 23.

The radius of surface 27 is less than that of lens surface 23 so that in forming lens 26, a flat surface 28 will be formed on the outer periphery of the anterior side of the lens as shown in FIGS. 3 and 4. Flat surface 28 lies in a plane that is parallel to the longitudinal axis 62 of the lens.

FIG. 4 illustrates the haptics utilized to secure the lens within the lens capsule. The haptics are formed in the manner disclosed in U.S. Pat. No. 6,261,321, the entire contents of which is hereby incorporated by reference thereto. Upper haptic 21 includes vertical legs 33, 34 and cross member 35 extending between legs 33 and 34. Upper haptic 51 also includes a pair of footplates 31 and 32. Legs 33, 34 and cross member 25 circumvent an opening 46. The footplates are preferably lentricular-shaped.

Lower haptic 22 is formed similar to haptic 51 and includes lower legs 43, 44 and cross member 45 extending between legs 43 and 44. The legs, cross member 45 and lower lens 26 circumvent opening 47. Lower haptic 52 also includes a pair of footplates 41 and 42 of lenticular shape.

Lenses 20 may be formed from a single body of a conventional material utilized for intraocular lens such as acrylic with twenty-six percent water. Lens surface 26 can be formed by using a Fast Tool System available from Ametek Precitech, Inc., located in Keene, New Hamshire. The conic bi-aspheric shape of the lens can be determined according to the methodology described in U.S. Pat. No. 7,350,918, the content of which is hereby expressly incorporated herein by reference thereto.

The distance optic on the multifocal surface is approximately 50 to 70 percent of the optical surface, and the near segment is about 50-30 percent of the optic, with the preferred distribution of optic being about 60 percent distance are 40 percent for near.

Although the present invention has been described with respect to specific details, it is not intended that such details should be regarded as limitations on the scope of the invention, except to the extent that they are included in the accompanying claims. 

I claim:
 1. A bifocal lens comprising: a posterior aspheric lens surface having a first radius, an anterior lens surface, said anterior lens surface having a first distance optic portion having a radius equal to the first radius of the posterior aspheric lens surface, a second near option portion having a radius less than that of the first portion thereby forming a second optic surface on the anterior lens surface; and the first distance optic portion having a perimeter and the second near optic having a perimeter, neither perimeter lying within the perimeter of the other optic portion; the anterior aspheric lens surface not including a substantially circular central part; and a flat surface located at the perimeter of the anterior lens near optic portion.
 2. (canceled)
 3. A bifocal lens as claimed in claim 2 wherein the flat surface lies in a plane which is parallel to the longitudinal axis of the lens.
 4. A bifocal lens as claimed in claim 1 where in the distance optic portion on the anterior surface is about 50% to 70% of the anterior surface of the lens and the near optic portion is about 50% to 30% of the anterior surface of the lens.
 5. The bifocal lens of claim 1 wherein the distance optic portion on the anterior surface is about 60% of the anterior surface and the near optic on the anterior surface is about 40% of the anterior surface.
 6. The bifocal lens of claim 1 further including haptics extending from the lens. 